Light Emitting Device Lattice Constant Stress Moderation

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Solution Overview

Problem

Light emitting devices, particularly those using quantum well structures, face inefficiencies due to compressive stress in the quantum well layer, which leads to poor spontaneous light emission efficiency and spatial separation of electrons and holes.

Innovation Solution

The implementation of a light emitting device structure where the face direction lattice constant of the semiconductor layers is adjusted such that the quantum barrier layer has a tensile stress and the quantum well layer has a compressive stress, with the semiconductor layer's lattice constant being greater than the quantum barrier layer's and smaller than the quantum well layer's, to moderate internal stress and enhance emission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the quantum well layer is formed with high indium content to improve light emission efficiency, then the spontaneous emission efficiency is improved, but the compressive stress in the quantum well layer increases causing spatial separation of electrons and holes

Engineering Contradiction:

Improvespontaneous emission efficiencyVSAvoidcompressive stress in quantum well layer

Core Design Contradiction:

Loss of energyVSStress or pressure

Solution Approach 1:

A composition gradient layer is introduced as an intermediary between the high-indium quantum well layer and the low-indium semiconductor layers. This gradient layer has an indium content that gradually transitions from the quantum well layer to the adjacent semiconductor layers, mediating the lattice constant difference and reducing compressive stress while preserving the high emission efficiency of the quantum well layer

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The indium content parameter is varied continuously in the composition gradient layer rather than being uniform. By changing the indium concentration parameter from high (near quantum well) to low (near adjacent semiconductor layers), the lattice constant is gradually adjusted, reducing the abrupt mismatch that causes compressive stress

Inventive Principle:

Principle #35Parameter changes

2Stress or pressure

If the lattice constant of semiconductor layers is increased to reduce compressive stress in quantum well layer, then the stress is moderated, but the lattice mismatch with quantum barrier layer increases

Engineering Contradiction:

Improvecompressive stress in quantum well layerVSAvoidlattice mismatch with quantum barrier layer

Core Design Contradiction:

Stress or pressureVSStability of the object's composition

Solution Approach 1:

The composition gradient layer is positioned locally between the quantum well layer and the adjacent semiconductor layers, providing localized stress relief only where needed. The quantum barrier layer maintains its original composition and lattice constant, preserving the sharp confinement potential required for efficient carrier confinement in the quantum well structure

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This stress moderation reduces the internal stress field in the quantum well layer, improving spontaneous emission efficiency and facilitating smoother electron and hole injection, resulting in a high-efficiency light emitting device.

Implementation Method 1

the face direction lattice constant of the first conduction type semiconductor layer or the second conduction type semiconductor layer is greater than the face direction lattice constant of the quantum barrier layer and smaller than the face direction lattice constant of the quantum well layer

Methodology Applied

Scientific EffectStress moderation through lattice constant adjustment:

Data Source

PatentUS9178108B2Light emitting device and light emitting device package

Publication Date: 2015.11.03 SUZHOU LEKIN SEMICON CO LTD

AI summary

The embodiment relates to a light emitting device and a light emitting device package, wherein the light emitting device includes a first conduction type semiconductor layer, an active layer formed on the first conduction type semiconductor layer, and a second conduction type semiconductor layer formed on the active layer, wherein the active layer includes a quantum well layer and a quantum barrier layer, and a face direction lattice constant of the first conduction type semiconductor layer or the second conduction type semiconductor layer is greater than the face direction lattice constant of the quantum barrier layer and smaller than the face direction lattice constant of the quantum well layer.